LG KM710 Service Manual page 51

4. Trouble Shooting
4.2.2.1 Mobile Switch & PAM & FEM Circuit
X400
U401
U403
FL400
SW400
<GSM850>
<GSM850>
LGE Internal Use Only
U400
U402
TX
LB_HB
TX_ANT_SW_EN
Mobile Switch
SW401 between C413
and C421 Is short?
YES
FEM
Check Control Signal
C422, C424
YES
Check R403, R404 RF LEVEL
≥ 0dBm
YES
Re-download SW & CAL
<PCS1900>
<PCS1900>
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NO
Replace SW400
NO
Check U401
NO
Check U402
TX
Only for training and service purposes